The present invention relates to an airbag system and a passenger restraint system for a vehicle and, more particularly, to an airbag system and a passenger restraint system for an automobile as a typical vehicle.
In recent years, automobiles as a typical vehicle have been increasingly popularly equipped with both driver- and passenger-side airbag systems. In order to attain fail safe of such airbag systems, for example, Japanese Utility Model Laid-Open No. 4-52956 discloses a method of always permitting airbags to inflate when a passenger detection sensor used for inflation control of airbags has failed. These airbag systems need to properly inflate in car crashes, but must not needlessly inflate in the absence of such emergencies in terms of labor and cost since exchange and adjustment are required once they have inflated. In the control of such airbag systems, it is important in, especially, the inflation control of the passenger-side airbag to check whether or not a passenger is sitting in the front passenger seat unlike the driver-side airbag, since often no passenger sits in the front passenger seat. In a vehicle equipped with a passenger-side airbag, another problem is posed in its inflation control when a so-called child seat for an infant is attached to the front passenger seat. When a child seat is attached facing front to the front passenger seat, the passenger-side airbag must be permitted to inflate, but when a child seat is attached facing rear, the passenger-side airbag must be inhibited from inflating since shocks to the child seat and an infant who is sitting in that child seat upon inflation of the passenger-side airbag must be prevented.
As a method of solving this problem, for example, Japanese Patent Laid-Open No. 7-165011 discloses a method of detecting the presence/absence of a child seat via communications with the child seat by arranging a transmission/reception mechanism in a seat.
The present applicants proposed a method associated with inflation control of a passenger-side airbag and signaling to a passenger in previous Japanese Patent Application Nos. 9-2130 and 9-2134, as a detailed and concrete method of solving the above-mentioned problem. These Japanese Patent Applications were filed in Japan on Jan. 9, 1997, which are not opened at present. Note, the Japanese Patent Application No. 9-2130 was filed on Jan. 7, 1998 as U.S. patent application Ser. No. 09/003,819 now U.S. Pat. No. 6,007,094 (inventor: HIROSHI HOSODA) corresponding to issued U.S. Pat. No. 6,007,094.
In order to assure higher safety, not only driver- and passenger-side airbags, but also so-called side airbags that can relax shocks from the sides of a vehicle onto passengers are required to be attached. Furthermore, in recent years, in order to attain both relaxation of restrained feeling experienced by a passenger in an ordinary state and secure restraint in an emergency state, a so-called seatbelt pretensioner for restraining a passenger by pulling in a seatbelt upon detecting shocks, and a so-called seatbelt load limiter for relaxing shocks onto the passenger by forming slack of the seatbelt in car crash have been developed.